Inotuzumab ozogamicin is an investigational antibody-drug conjugate (ADC), which features a monoclonal antibody (mAb) targeting CD22,9 cell surface antigen expressed on about 90% of B-cell malignancies,10 linked to a cytotoxic agent.
Pfizer said when inotuzumab ozogamicin binds to the CD22 antigen on malignant B-cells, it is internalized into the cell, where the cytotoxic agent calicheamicin is released to destroy the cell.
The Phase 3 study of inotuzumab ozogamicin met its first primary endpoint in adult patients with relapsed or refractory CD22-positive ALL.
Pfizer Oncology senior vice president of clinical development and medical affairs and chief medical officer Mace Rothenberg said: "Inotuzumab ozogamicin is the third Pfizer oncology medicine to be granted Breakthrough Therapy designation by the FDA, underscoring our commitment to innovative research and development that addresses significant unmet needs.
"Advancing therapies for patients with adult acute lymphoblastic leukemia is crucial as only 10 percent of adults with ALL who relapse after first-line therapy survive five years or more with current treatment options."
It is estimated that 6,250 cases of ALL will be diagnosed in the US this year, with about 1 in 3 cases in adults.
Only about 20% to 40% of newly diagnosed adults with ALL are cured with existing treatment regimens.